Sander providing airflow correction

ABSTRACT

A sander capable of correcting airflow amount comprises a body and a correction valve. The body includes an air intake passage to receive pressurized air, a drive motor driven by the pressurized air to rotate at a rotational speed including a preset range and an excessive range, and a regulation valve located on the air intake passage to adjust the rotational speed of the drive motor in the preset range. The correction valve includes an adjustment portion operable in an adjustment displacement and a mask wall movable by the adjustment portion to block the air intake passage. The adjustment portion determines the flow amount of the pressurized air passing through the correction valve according to the adjustment displacement thereof to confine the rotational speed of the drive motor from the excessive range to the preset range, thereby controls the rotational speed of the drive motor in the preset range.

FIELD OF THE INVENTION

The present invention relates to a sander and particularly to a sander capable of correcting airflow amount.

BACKGROUND OF THE INVENTION

A conventional machine tool usually is made in a small size and can be coupled with different application tools to provide various types such as a grinder, sander, drilling machine, electric wrench and the like. Such a machine tool can aid users to quickly grind the surface of articles to make it smooth and flat. The machine tool can be an electric machine tool driven by electric power or a pneumatic machine tool driven by pressurized air. The conventional pneumatic sander mainly employs the pressurized air as the power source to drive a sanding tool. During sanding operation air is circulated inside the pneumatic sander. The air has air pressure to drive the sanding tool to rotate. While the sanding tool is rotated, the air also must be discharged from the interior of the pneumatic sander. Discharge of the air generates noises.

To solve the noise problem caused by discharge of air in the pneumatic sander, TW patent No. M352423 discloses a machine tool noise muffling structure. It comprises a cap with a plurality of apertures formed thereon and at least one post extended upwards from the cap. The post is attached by noise muffling cotton. The cap and noise muffling cotton are interposed by an air discharge space to discharge air and muffle the noise. While the muffling cotton can be installed in an exhaust tube of the sander to reduce the noise caused by discharge of the air, muffling cotton also impedes air circulation and reduces airflow speed or amount that result in the problem of lowering rotational speed of the drive motor.

SUMMARY OF THE INVENTION

The primary object of the present invention is to avert the problem of the machine tools having reduced airflow amount to lower rotational speed of the motor caused by block of the airflow due to installation of components in the air passage.

To achieve the foregoing object, the present invention provides a sander capable of correcting airflow amount. The sander comprises a body and a correction valve. The body includes an air intake passage to receive pressurized air, a drive motor driven by the pressurized air to rotate at a rotational speed including a preset range and an excessive range, and a regulation valve located on the air intake passage and operable manually by a user to adjust the rotational speed of the drive motor in the preset range. The correction valve is located in the air intake passage and coupled with the regulation valve. The correction valve is installed on the air intake passage and coupled with the regulation valve, and includes an adjustment portion operable by a mechanical tool to proceed an adjustment displacement and a mask wall movable by the adjustment portion to block the air intake passage. The adjustment portion determines the flow amount of the pressurized air passing through the correction valve according to the position thereof during the adjustment displacement to confine the rotational speed of the drive motor from the excessive range to the preset range.

In one embodiment the proportion of the excessive range to the preset range is less than 30%.

In another embodiment the air intake passage has a positioning notch to hold the correction valve.

In yet another embodiment the correction valve is fixedly held in the positioning notch via a clip ring.

In yet another embodiment the mask wall has an airflow directing hole to allow the pressurized air to pass through.

In yet another embodiment the body includes an activation valve stem located on the air intake passage and the air intake passage has an air nozzle to block the pressurized air from entering the regulation valve. By pressing the activation valve stem, the air nozzle is driven to deviate against the regulation valve so that the pressurized air can pass through the regulation valve.

In yet another embodiment the body includes an activation member which butts the activation valve stem and is depressible by a user to move the activation valve stem downwards so that the air nozzle is deviated against the regulation valve.

In yet another embodiment the body includes a sanding disk driven by the drive motor to rotate in a rotational displacement.

In yet another embodiment the regulation valve includes a control portion operable manually by a user, and a throttle wall extended from the control portion to the air intake passage and operable by the user to determine degree of masking the air intake passage, and an airflow regulation port formed on the throttle wall to allow the pressurized air to pass through.

In yet another embodiment the air intake passage includes an air intake duct to allow the pressurized air to enter the regulation valve. The correction valve is located between the regulation valve and drive motor to receive the pressurized air from the regulation valve and send to the drive motor.

The invention, compared with the conventional techniques, provides many advantages, notably:

1. The air intake passage is provided with a correction state (i.e. excessive range).

2. The problem of reduced airflow amount to lower rotational speed of the motor caused by block of the airflow due to installation of components in the air passage can be resolved.

The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the sander providing airflow correction according to the invention.

FIG. 2 is a sectional view of the sander providing airflow correction according to the invention.

FIG. 3A is a schematic view of the sander of the invention with the correction valve fully open.

FIG. 3B is a schematic view of the sander of the invention with the correction valve half-open.

FIG. 4 is a schematic view of the sander of the invention in a use condition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Please refer to FIGS. 1, 2 and 4, the present invention aims to provide a sander capable of correcting airflow amount. The sander mainly comprises a body 1 and a correction valve 2. The body 1 includes an air intake passage 11, a drive motor 12, a sanding disk 13, a regulation valve 14, a positioning notch 15, an activation valve stem 16, an activation member 17 and an air nozzle 18. The drive motor 12 is driven by pressurized air to rotate. The sanding disk 13 is driven by the drive motor 12 to proceed a rotational displacement. The drive motor 12 is rotated at a rotational speed including a preset range and an excessive range. The proportion of the excessive range to the preset range is less than 30%. The air intake passage 11 contains an air intake duct 111 to direct the pressurized air into the body 1. The activation valve stem 16 is located on the air intake passage 11. The air intake passage 11 also contains the air nozzle 18 to block the pressurized air from entering the regulation valve 14 via the air intake duct 111. The activation valve stem 16 butts the activation member 17 so that a user can press the activation member 17 to drive the activation valve stem 16 to move downwards, and consequently move the air nozzle 18 to deviate against the regulation valve 14 to allow the pressurized air to pass through the regulation valve 14. The regulation valve 14 is located on the air intake passage 11 and includes a control portion 141 operable by a user's hand 3, a throttle wall 142 extended from the control portion 141 towards the air intake passage 11 and operable by the user to determine degree of masking the air intake passage 11 as desired, and an airflow regulation port 143 formed on the throttle wall 142 to allow the pressurized air to pass through to allow the user to adjust the rotational speed of the drive motor 12 in the preset range. Thus the regulation valve 14 has an air supply state in which the user turns the control portion 141 to allow the pressurized air to pass through the regulation valve 14 in a preset range of the rotational speed of the drive motor 12, and an air supply stopping state in which the user turns the control portion 141 to allow the throttle wall 142 to block the pressurized air from passing through the airflow regulation port 143.

The correction valve 2 is located on the air intake passage 11 and connected to the regulation valve 14, and includes an adjustment portion 21, a mask wall 22 and an airflow directing hole 23 formed on the mask wall 22 to allow the pressurized air to pass through. The adjustment portion 21 is operable by a mechanical tool 4 to proceed an adjustment displacement. Moreover, the adjustment portion 21 drives the mask wall 22 to block the air intake passage. Hence the flow amount of the pressurized air passing through the correction valve 2 is determined according to the position of the adjustment portion 21 during the adjustment displacement, thereby the rotational speed of the drive motor 12 can be confined from the excessive range to the preset range.

Please refer to FIGS. 3A and 3B for the correction valve of the sander in a fully open state and a half-open state. In this embodiment, the air intake passage 11 has a positioning notch 15, and the correction valve 2 is fixedly held in the positioning notch 15 through a clip ring 19. The proportion of the excessive range to the preset range of the drive motor 12 is less than 30%. For instance, given the maximum rotational speed upper limit of the drive motor 12 is at 11,000 rpm, if the preset rotational speed of the drive motor 12 is 10,000 rpm, the excessive rotational speed of the drive motor 12 can be adjusted to 10,000 rpm through the correction valve 2, i.e., when the pressurized air enters the body 1 via the air intake duct 111, user can press the activation member 17 to move the activation valve stem 16 downwards, and the air nozzle 18 also is moved to deviate against the regulation valve 14 so that the pressurized air can pass through the regulation valve 14. Then, user can turn the control portion 141 by his hand 3 to adjust the throttle wall 142 so that the pressurized air can be blocked from passing through the airflow regulation port 143 or pass through the airflow regulation port 143 due to the communication between the airflow regulation port 143 and air intake passage 11, thereby adjust the rotational speed of the drive motor 12 in the preset range. Next, through the mechanical tool 4 wedged in the adjustment portion 21 of the correction valve 2 to execute an adjustment displacement, namely, the mask wall 22 is driven by the adjustment portion 21 to block the air intake passage 11, such as the mask wall 22 does not block the air intake passage 11 (referring to FIG. 3A) or the adjustment portion 21 is turned to allow the mask wall 22 to block half of the air intake passage 11 (referring to FIG. 3B), the pressurized air enters from the air intake duct 111 into the regulation valve 14 and is adjusted accordingly. Since the correction valve 2 is located between the regulation valve 14 and drive motor 12 to transmit the pressurized air to the drive motor 12, the flow amount of the pressurized air can be adjusted via the adjustment displacement of the correction valve 2 to confine the rotational speed of the drive motor 12 from the excessive range to the preset range, thereby resolve the problem of reduced airflow amount to lower rotational speed of the drive motor caused by block of airflow due to installation of components (such as adding noise muffling cotton in the exhaust tube) in the air passage. Moreover, as the assembly elements in batch production could have variances in material weight or dimension, the airflow amount could also have errors. However, it can be resolved by confining the rotational speed of the drive motor 12 from the excessive range to the preset range through the adjustment displacement provided by the correction valve 2, thereby improve production yield.

As a conclusion, the sander capable of correcting airflow amount of the invention mainly includes a body and a correction valve. The body includes an air intake passage to receive pressurized air, a drive motor driven by the pressurized air to rotate at a rotational speed including a preset range and an excessive range, and a regulation valve located on the air intake passage and operable manually by users to adjust the rotational speed of the drive motor in the preset range. The correction valve is located on the air intake passage and coupled with the regulation valve, and includes an adjustment portion operable by a mechanical tool to proceed an adjustment displacement and a mask wall movable by the adjustment portion to block the air intake passage. Based on the location of the adjustment portion during the adjustment displacement, the flow amount of the pressurized air passing through the correction valve can be determined to confine the rotational speed of the drive motor from the excessive range to the preset range, thus resolve the problem of reduced airflow amount to lower rotational speed of the drive motor caused by block of airflow due to installation of component in the air passage. 

What is claimed is:
 1. A sander providing airflow correction, comprising: a body including an air intake passage to receive pressurized air, a drive motor driven by the pressurized air to rotate at a rotational speed including a preset range and an excessive range, and a regulation valve located on the air intake passage and operable manually by a user to adjust the rotational speed of the drive motor in the preset range; and a correction valve which is located on the air intake passage and coupled with the regulation valve, and includes an adjustment portion operable by a mechanical tool to proceed an adjustment displacement and a mask wall movable by the adjustment portion to block the air intake passage, the adjustment portion determining flow amount of the pressurized air passing through the correction valve according to the position thereof during the adjustment displacement to confine the rotational speed of the drive motor from the excessive range to the preset range.
 2. The sander of claim 1, wherein the proportion of the excessive range to the preset range is less than 30%.
 3. The sander of claim 1, wherein the air intake passage includes a positioning notch to hold the correction valve.
 4. The sander of claim 3, wherein the correction valve is fixedly held in the positioning notch through a clip ring.
 5. The sander of claim 1, wherein the mask wall includes an airflow directing hole to allow the pressurized air to pass through.
 6. The sander of claim 1, wherein the body includes an activation valve stem located on the air intake passage, the air intake passage including an air nozzle to block the pressurized air from entering the regulation valve, the activation valve stem being depressible to drive the air nozzle to deviate so that the pressurized air passes through the regulation valve.
 7. The sander of claim 6, wherein the body includes an activation member which butts the activation valve stem and is depressible to move the activation valve stem downwards so that the air nozzle is deviated against the regulation valve.
 8. The sander of claim 1, wherein the body includes a sanding disk driven by the drive motor to rotate in a rotational displacement.
 9. The sander of claim 1, wherein the regulation valve includes a control portion operable manually by the user, a throttle wall extended from the control portion to the air intake passage and operable by the user to determine degree of masking the air intake passage, and an airflow regulation port formed on the throttle wall to allow the pressurized air to pass through.
 10. The sander of claim 1, wherein the air intake passage includes an air intake duct to direct the pressurized air into the regulation valve, the correction valve being located between the regulation valve and the drive motor to transmit the pressurized air from the regulation valve to the drive motor. 